This project is designed to maintain collaborative studies in the field of cancer chemotherapy as an active member of the Acute Leukemia Cooperative Group B. The participating members are involved in collaborative investigations in the field of experimental therapeutics in patients with a variety of neoplastic diseases including childhood leukemia and malignant solid tumors of children. These studies will concern the evaluation of activity of a number of compounds thought to have therapeutic potentials in human cancer. The methods used involve carefully designed protocols; the data obtained will be submitted to critical analysis at periodically combined meetings and statistical evaluation.